1. Field of the Invention
The present invention relates to a magnetic flux converging type high speed electromagnet of efficient magnetic excitation and shortened response time.
2. Related Art Statement
As is well known, in the conventional electromagnet, the following methods (a ) and (b) are generally adopted for attaining high speed action:
(a) Supplying a large current to an exciting coil for increasing the attracting force of the magnet.
(b) Shortening the response time by increasing the resistance of an exciting coil for reducing the time constant thereof, particularly in a high speed electromagnet utilized for a high speed relay and other applications.
Accordingly, whichever methods (a) and (b) is adopted, it is required to supply a high voltage to the exciting coil.
However, after the attraction has been effected by the electromagnet, the function thereof can be sufficiently maintained even by a small exciting current. Thus, the electric power supplied by a high voltage source for the initial attraction is not needed thereafter and hence is almost entirely wasted.
Moreover, when method (a) is adopted, even if the magnetomotive force is strengthened by supplying a large current to the exciting coil, so as to increase the amount of magnetic flux, the leakage magnetic flux is relatively increased. Consequently, method (a) has an avoidable defect in that the effective magnetic fluxes required for attraction are reduced in response to the increase of leakage magnetic flux.
On the other hand, if method (b) is adopted, the same defect as in the above case cannot be avoided.